α-Synuclein is part of a large family of proteins including β- and γ-synuclein and synoretin. α-Synuclein is expressed in the normal state associated with synapses and is believed to play a role in neural plasticity, learning and memory. Several studies have implicated α-synuclein with a central role in Parkinson disease pathogenesis. Molecular changes in the α-synuclein protein that increase protein misfolding and aggregation have a direct role in disease pathogenesis. Aggregation of α-synuclein contributes to the formation of Lewy bodies and neutrites, the pathologic hallmarks of Parkinson disease and α-synucleinopathies. Activation of tyrosine kinase c-abl contributes to α-synuclein-induced neurodegeneration.
The tyrosine kinase c-abl is tightly regulated non-receptor protein tyrosine kinase involved in a wide range of cellular processes, including growth, survival and stress response (Nat Rev Mol Cell Biol, 2004, 5:33-44) and c-abl involved in regulation several cellular processes and has implicated in the development of the central nervous system by controlling neurogenesis. More recently, increasing evidence from various experimental model systems has also revealed that c-abl is activated in neurodegenerative disease such as Alzheimer's disease, Parkinson's disease, Niemann-Pick type C diseases and tauopathies. (Human Molecular Genetics, 2014, Vol. 23, No. 11)
The stress-signaling non-receptor tyrosine kinase c-abl links parkin to sporadic forms of Parkinson's disease via tyrosine phosphorylation. Tyrosine phosphorylation of parkin by c-abl is a major post-translational modification that leads to loss of parkin function and disease progression in sporadic Parkinson disease. Inhibition of c-abl offers new therapeutic opportunities for blocking Parkinson disease progression. (The Journal of Neuroscience. 2011, 31(1): 157-163) Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by progressive death of motor neurons. Knockdown of c-abl with small interfering RNAs (siRNAs) also rescued ALS motor neuron degeneration. (Imamura et al., Sci. Transl. Med. 9, 2017) Multiple System Atrophy (MSA) is a rare, rapidly progressive neurodegenerative disease without any current treatment. In MSA there is accumulation of α-synuclein in the neurons and oligodendrocytes of the substantia nigra, striatum, olivopontocerebellar structures and spinal cord. (J Neural Transm Vienna Austria 1996. 2016:123(6)).
Administration of the tyrosine kinase inhibitor nilotinib decreases c-abl activity and ameliorates autophagic clearance of α-synuclein in transgenic and lentiviral gene transfer models. Activation of c-abl in the mouse forebrain induces neurodegeneration in the hippocampus and striatum. Therefore, an increase in c-abl activity via phosphorylation may be associated with the α-synuclein pathology detected in Parkinson disease and other neurodegenerative disease. (Hum Mol Genet. 2013 Aug. 15).
U.S. Ser. No. 16/148,165 describes benzothiazol compounds as a c-abl inhibitor that is useful for the treatment of a disease or disorders such as α-synucleinopathy, Parkinson disease, Alzheimer disease, ALS, Dementia with Lewy body and MSA. The present disclosure describes a process and method for preparing and purifying the benzothiazol compound. The method may avoid excessive formation of byproducts during the reaction, improve the yield, and/or simplify the purification process.